title: Biosensor for neurotransmitter L-glutamic acid designed for efficient use of L-glutamate oxidase and effective rejection of interference.
abstract: An amperometric biosensor for L-glutamic acid (Glu) was constructed by the adsorption and dip coating of L-glutamate oxidase (GluOx, 200 U ml-1 phosphate buffer, pH 7.4) onto 60-micron radius Teflon-coated Pt wire (1 mm exposed length). The enzyme was then trapped on the surface by electropolymerisation of o-phenylenediamine that also served to block electroactive interference. This procedure afforded electrodes with similar substrate sensitivity compared with the classical approach of immobilising enzyme from a solution of monomer, and represents an approximately 10,000-fold increase in the yield of biosensors from a batch of enzyme. A number of strategies were examined to enhance the sensitivity and selectivity of the Pt/PPD/GluOx sensors operating at 0.7 V versus SCE. Pre-coating the Pt with lipid and incorporation of the protein bovine serum albumin into the polymer matrix were found to improve the performance of the electrode. The sensors had a fast response time, high sensitivity to Glu, with an LOD of about 0.3 mumol l-1, and possessed selectivity characteristics suggesting that monitoring Glu in biological tissues in vivo may be feasible.
authors.affiliation: Department of Chemistry, University College Dublin, Belfield, Ireland.
authors.forename: M R
authors.initials: MR
authors.lastname: Ryan
authors.forename: J P
authors.initials: JP
authors.lastname: Lowry
authors.forename: R D
authors.initials: RD
authors.lastname: O'Neill
mesh_terms: D000594:Amino Acid Oxidoreductases; D015374:Biosensing Techniques; D001923:Brain Chemistry; D004563:Electrochemistry; D005110:Extracellular Space / Q000737:chemistry; D018698:Glutamic Acid / Q000032:analysis*; D006801:Humans; D010655:Phenylenediamines
chemical_list: D010655:Phenylenediamines; D018698:Glutamic Acid; D000594:Amino Acid Oxidoreductases; C023061:L-glutamate oxidase